Refrigeration oil composition having wide boiling range

ABSTRACT

A wide boiling range e.g., for a given VGC) refrigeration oil, having good chemical and thermal stability and good miscibility with fluorinated hydrocarbon refrigerants, comprises a blend of from 50-75 volume percent of hydrorefined naphthenic oil component and 50-25 volume percent of solvent refined and dewaxed paraffinic oil component. Preferably, the hydrorefined naphthenic oil component (which can be a blend of two or more hydrorefined oils) has an SUS viscosity at 100* F. in the range of 75-750 SUS and the paraffinic oil component (which can be a blend) is chosen so that the resulting naphthenic paraffinic blend has a viscosity at 100* F. in the range of 100-500 SUS (preferably 125-300 SUS, typically 150-250 SUS) and has a maximum natural floc point of 35* F. Preferably the blend contains less than 10 ppm (more preferably less than 5) of basic nitrogen and contains in the range of 15-35 weight percent aromatics.

United States Patent 1191 Mills et al.

[ Feb. 6, 1973 1 1 REFRIGERATION OIL COMPOSITION HAVING WIDE BOILING RANGE [75] lnventors: Ivor W. Mills; John J. Melchiore, Marcus Hook, Pa.

[73] Assignee: Sun Oil Company, Philadelphia, Pa.

[22] Filed: Aug. 12, 1970 [2]] Appl. No.: 63,303

Primary Examiner-Herbert Levine AttorneyGerge L. Church, Donald R. Johnson, Wilmer E. McCorquodale, Jr. and Barry A. Bisson 7 ABSTRACT A wide boiling range e.g., for a given VGC) refrigeration oil, having good chemical and thermal stability and good miscibility with fluorinated hydrocarbon refrigerants, comprises a blend of from -75 volume percent of hydrorefined naphthenic oil component and 50-25 volume percent of solvent refined and dewaxed paraffinic oil component. Preferably, the hydrorefined naphthenic oil component (which can be a blend of two or more hydrorefined oils) has an SUS viscosity at 100 F. in the range of 75-750 SUS and the paraffinic oil component (which can be a blend) is chosen so that the resulting naphthenic paraffinic blend has a viscosity at F. in the range of 100-500 SUS (preferably -300 SUS, typically -250 SUS) and has a maximum natural floc point of 35 F. Preferably the blend contains less than 10 ppm (more preferably less than 5) of basic nitrogen and contains in the range of 15-35 weight percent aromatics.

9 Claims, N0 Drawings REFRIGERATION OIL COMPOSITION HAVING WIDE BOILING RANGE CROSS REFERENCE TO RELATED APPLICATIONS The following patents and applications, all assigned to The Sun Oil Company (as is the present application), are related to the disclosure of the present application in that they disclose methods of obtaining hydrorefined naphthenic oils, dewaxed paraffinic oils and methods of reducing the basic nitrogen content of component oils which can be used to make the blended refrigeration oil composition of the present invention. Other methods for obtaining hydrorefined naphthenic and dewaxed paraffinic oils, useful as such blending components, are well known to the art.

The disclosure of all of the following applications and patents is hereby incorporated in the present application:

Issue Date Patent No.

Serial No.

Filing 3-13-67 3,462,358 8-19-69 Clay Treatment of Hydro-refined Cable Oils IVOR W. MILLS & GLENN R. DIMELER Process for Preparing an Aromatic Oil and Nondiscoloring Rubber Compo-sition Containing Said Oil IVOR W. MILLS,

GLENN R. DIMELER 8!. MERRITT C. KIRK, JR.

Process for Producing Cable Oils by Sequential Refining Steps IVOR W. MILLS & GLENN R. DIMELER Rubber Containing Acid-Treated Oils and Its Preparation ABRAHAM SCHNEIDER & ARCHIBALD P. STUART Hydrorefined Transformer Oil and Process of Manufacture IVOR W. MILLS & GLENN R. DIMELER Catalytic Hydrofinishing of Petroleum Distillates in the Lubricating Oil Boiling Range IVOR W. MILLS, MERRITT C. KIRK. JR. 8L ALBERT T. OLENZAK I lsomerization of Waxy Lube Streams and Waxes IB STEINMETZ & DAVID S. BARMBY Blended Hydrocarbon Oil and Process of Manufacture IVOR W. MILLS & GLENN R. DIMELER BACKGROUND AND SUMMARY OF THE INVENTION High temperature compressors operating with prior art naphthenic refrigeration oils develop coke deposits in the throttle valves. Apparently, these coke deposits are initiated by small particles of Mylar or other synthetic materials which are suspended or solubilized in the oil but deposit on the throttle valves because the oil vaporizes on hot spots. The deposits initiate decomposition of the refrigeration oil and cause it to coke.

A possible solution to this coking problem is to make a refrigeration oil with a high boiling point. One means of obtaining a higher boiling point is to use a paraffinic rather than a naphthenic oil. Refrigeration oils have been marketed which apparently consist of a paraffinic oil which has been acid treated. These oils usually contain some aromatics and although high boiling, have a narrow boiling range. In general, such paraffinic refrigeration oils lack the chemical stability of naphthenic refrigeration oils and/or they have a high floc point and poor miscibility with refrigerants (e.g. R-l2).

The present invention relates to a refrigeration oil which has good chemical stability and also good thermal stability and which has a wider boiling range for a given VGC than does a prior art paraffinic refrigeration oil. The novel oil also retains a floc point no greater than 35 F. (more preferred less than 40 F.), has good miscibility with conventional refrigerants, has good sealed tube stability and permits the operation of compressors at higher operating temperatures (e.g. a coil temperature above 125 C.) than do present refrigeration oils.

A wide boiling range (e.g. for a given VGC) refrigeration oil of the present invention, having good chemical and thermal stability and good miscibility with fluorinated hydrocarbon refrigerants, comprises a blend of from 50-75 volume percent of hydrorefined naphthenic oil component and 50-25 volume percent of a dewaxed paraffmic oil component. Preferably, the hydrorefined naphthenic oil component (which can be a blend of two or more hydrorefined oils) has an SUS viscosity at 100 F. in the range of 75-750 SUS and the paraffmic oil component is chosen so that the resulting naphthenic-paraffinic blend has a viscosity at 100 F. in the range of 100-500 SUS (preferably 125-300 SUS, typically l50-250 SUS) and has a maximum natural (e.g. does not contain a pour point depresant) floc point of 35 F. Preferably the blend contains less than ppm (more preferably less than 5) of basic nitrogen and contains in the range of -35 weight percent aromatics. The paraffinic oil component can contain or consist of hydrorefined paraff'mic oil having a low wax content. The hydrorefined naphthenic component can be a raffinate from solvent extraction (either before or after hydrorefming), as with furfural, to reduce the aromatic content.

The novel oil can be made by blending a low basic nitrogen content paraffinic oil (having a viscosity at 100 F. of about 500 SUS) with a low basic nitrogen content hydrorefined naphthenic oil (e.g. having an SUS viscosity at 100 F. of about 150). A preferred process for insuring a low basic nitrogen content (e.g. less than 5 ppm, typically 1 ppm or less) in the naphthenic and paraffinic components and/or in the blend comprises acid or acid-clay contacting the blend and/or one or more of the component oils. For example, the Lewis acid contacting (preferably with neutralization) of the aforementioned applications Serial Nos. 622,398 (now US. Pat. No. 3,462,358); 652,026 (now U.S. Pat. No. 3,502,567); 657,438; 850,717 and 850,779. A preferred method of reducing the basic nitrogen in a blend of a hydrorefined naphthenic oil and a dewaxed paraffinic oil or in one or both of these component oils is to contact the oil with an adsorbent comprising an acid-activated absorbent clay, more preferably an admixture or combination of an acid-activated absorbent clay and a fullers earth bleaching clay such as attapulgite. Useful adsorbent admixtures and process conditions for such contacting are disclosed in U.S. Pat. No. 3,369,999, for the decolorizing of waxes.

FURTHER DESCRIPTION One important test of refrigeration oil quality is the floc point, which is a measure of the tendency of wax separation from the oil under conditions which simulate actual operation in a refrigeration system. A second important test, which can be correlated with actual use conditions, is the 14-day sealed tube stability test.

The floc point is the temperature at which a floc of wax or other solid substances separates from a 10 percent mixture of the oil in R-12 refrigerant (CCI F Lint-like floc is to be contrasted with cloud-like haze. The test apparatus comprises a 15 ml graduated tube, 27.9 cm X 14 mm with 2 mm thick walls, a pressure tube holder, a cooling bath, a thermometer, and a cooling coil. The cooling bath can be large, wide mouth Dewar flask (Fisher Scientific Co. No. 14-197, Size 2, is satisfactory). Dry ice and acetone are used as the cooling medium. The thermometer can be ASTM Low Cloud and Pour 6F, having the range -1 12 to F. The R-l2 cooling coil is made of one-fourth inch copper tubing, and is immersed in the dry ice acetone bath to chill the refrigerant to below -25 F. so that it may be charged as liquid to the graduated tube containing the sample. In this test, a sample of the oil to be tested is charged to a graduated glass tube and chilled refrigerant is added. The tube is sealed in the tube holder and the system is allowed to warm enough to become homogeneous on shaking. The mixture is then cooled in a chilling bath until there is a distinct floc present in it. The temperature at that point is reported as the floc point. Since considerable pressure is developed in the glass tube during the test, the tube should be wrapped with a cloth towel when it is removed from the cooling bath. The operator should wear a protective face mask.

The procedure involves pipeting 1 cc of the oil to be tested tothe glass tube. The glass tube and sample are inserted into the pressure tube holder and the assembly is immersed into the cooling bath and chilled to a temperature below the boiling point of the refrigerant (-25 F for R-l2). The refrigerant is condensed by passing it slowly through the copper cooling coil and the liquid is added to the cooled sample tube until the liquid level reaches the 10 cc mark on the tube. That is, total volume of the oil-refrigerant mixture is 10 cc. The charged tube is then tightly sealed and allowed to warm up to a temperature sufficiently high to permit making the system homogeneous by shaking. The assembly with the refrigerant-sample mixture is then cooled in the dry ice-acetone bath. The temperature of the bath is lowered at a rate of approximately 1 or 2 Fahrenheit per minute by careful addition of dry ice. Observations are made at 1 intervals, beginning at 0 F. When such observations first reveal a distinct flocculent material suspended in the mixture, the reading of the test thermometer in the bath is recorded as the floc point. This floc point test is reproducible within at least 2 F. Some oilsshow a haze at a temperature slightly above the floc point temperature. This temperature is usually 5 to 10 above the actual floc point. If a test oil clouds at about 0 F, the test should be repeated to be certain that moisture has not been inadvertently introduced into the test apparatus.

The second important test, the 14-day sealed tube stability, rates the quality of a refrigeration oil by evaluation of the appearance of the oil and a metal test strip, and the amount of reaction of an oil with a halogenated refrigerant after aging in a sealed tube.

Since oil and gases are under pressure in the glass tubes, the tubes should be treated as though they might explode at any time. Safety glasses, a plastic face shield and heavy leather gloves should be worn when handling a sealed tube.

The method consists of sealing 5 ml of an oil, R-12 refrigerant, and a steel strip in a heavy-walled glass tube which is then heated in an oven to 347+ 1 F. and aged at the temperature for 14 days. The oil is rated on appearance at 14 days. After 14 days the tubes are opened and the contents analyzed by vapor phase chromatography for the percentage of R-22 and R-12, thus determining the composition of R-l2 (CCl F to R-22 (CHClF The detailed procedure for the sealed tube stability test is well known in the refrigeration manufacturing and petroleum refining industries. For example, the procedure was reported and published in print by H. O. Spauschus and G. C. Doderer, at the 73rd ASHRAE Annual Meeting, Toronto, Ontario, June 28, 1966.

In the oil of the present invention, it is important that either the blended oil or all ofits components be as free of basic nitrogen as is practical. Preferred means of reducing basic nitrogen being contacting with acid (e.g. H 50 and neutralization, or by contacting with an acid-activated clay (preferably a mixture of acid-activated clay and attapulgite). Such contacting to reduce the basic nitrogen in the oil insures good 14 day sealed tube stability (e.g. maximum of 2.5 percent R-22, more preferably 1.5 percent maximum, typically less than 1.0 percent).

The acid or acid clay treatment of the paraffinic component also causes improved results in the Falex failure load test, which is a test to determine lubricating quality of a refrigeration oil.

ILLUSTRATIVE EXAMPLES In the following examples, SUS viscosity is at 100 F. and parts are by volume, unless otherwise indicated.

EXAMPLE 1 A hydrorefined naphthenic oil component having a viscosity of 150 SUS was obtained by blending 100 SUS and 500 SUS hydrorefined naphthenic oils. Each of these oils was obtained by severe hydrorefining (as defined in US. Pat. No. 3,462,358) of naphthenic acidfree naphthenic distillate. The hydrorefining was at 625 F., 1,200 psig of 80 percent hydrogen, 0.25 LHSV, in the presence of sulfided NiMo oxide catalyst. The 150 SUS blended composition was contacted at about 240 F. with a mixture, per barrel of oil, of pounds of acid-activated clay and 10 pounds of attapulgite. The resulting clay contacted 150 SUS hydrorefmed naphthenic oil contained less than 1 ppm of basic nitrogen.

A Duosol solvent refined and methylethyl ketone dewaxed (to a pour point of 0 F.) paraffinic lube distillate, having a SUS viscosity of 500, was contacted at 240 F. with a mixture, per barrel of oil, of 10 pounds of acid-activated clay and 10 pounds of attapulgite. The resulting 500 SUS paraffinic component contained less than 1 ppm of basic nitrogen.

A blended refrigeration oil, of the present invention, was obtained by blending 68 parts by volume of the 150 SUS hydrorefined naphthenic oil component and 32 parts of the 500 SUS paraffinic component. The properties of this blended refrigeration oil are reported in Table 1, along with a typical range of properties of a preferred blended refrigeration oil composition.

Table 2 hereof reports the distillation ranges in F., obtained under vacuum and corrected to at l atmosphere, of the hydrorefined naphthenic component, the refrigeration oil blend and the dewaxed paraffinic component. Note the wide boiling range of the blended refrigeration oil, compared with the boiling range of each component. In one preferred embodiment, at least volume percent of the naphthenic component will distill below 800 F., corrected to 1 atmosphere, and at least 80 volume percent of the paraffinic component will distill above 800 F., corrected to one atmosphere the latter requirement being the most important. More preferred, at least 50 percent of the paraffinic component should boil above 900 F.

EXAMPLE 2 A blended refrigeration oil was obtained as in Example 1, except that the blend contained 63 parts of the 150 SUS hydrorefined naphthenic oil component and 37 parts of the 500 SUS dewaxed paraffinic component. This blended refrigeration oil had the same properties as those reported in Table l for the oil of Example 1 except that the viscosity at F. was 235, the pour point was 25 F., the aniline point was l99.8 F. and the weight percent (gel) aromatics was 27.5.

The performance of the blended refrigeration oil of this example was evaluated after 2,000 hours of operation with R-l 2 in a compressor at a coil temperature of about 160 C. The condition of the Mylar, the valves, the copper plating on the shafts and of the other operating parts after the 2,000 hours was significantly better than the condition of similar parts from a compressor run for 2,000 hours at 160 C. using a conventional naphthenic refrigerant (which failed before 2,000 hours).

In another series of use tests, the blended refrigeration oil of this example was compared with a low basic nitrogen content dewaxed paraffinic refrigeration oil and with a refrigeration oil comprising 60 percent alkylated benzene and 40 percent mineral oil. The tests were run for 3 months at 160C. winding temperature. The naphthenic-paraffinic blend of the present invention exhibited better wear and life properties than did the other two oils.

This was a severe test of thermal stability since these compressors normally operate within the l40 C. temperature range. Generally, prior art naphthenic refrigeration oils are used in compressors where the temperature is in the 100-110 C. range.

Sulfates D878 None Basic Nitrogen, ppm 1 less Free Sulfur D989 None than 5 Corrosive Sulfur; Class Dl275 No. 1 Total Sulfur, D129 0.04 Aniline Point, F. D61 l 195 Refractive Index Dl747 l.4945 Aromatics, Gel. Fine, F. -47 max Power Factor/25C., Initial D924 0.00l PowerFactorl i 00C., lnitial D924 0.0086 14-Day Sealed Tube, wt.& R'22 0.6 1.0 max ASTM Test Designations F Ice and sealed tube tests are with R-l2 refrigerant and are described in this specification. The basic nitrogen test is described in Serial No. 850,779.

TABLE 2 DISTlLLATlON RANGES FOR EXAMPLE 1 COMPONENTS AND BLEND F. at 760 MM* The distillations were made at reduced pressure and corrected (or extrapolated) to one atmosphere.

The invention claimed is:

l. A composition, useful as a refrigerator oil, comprising a blend of from 50-75 volume percent of a hydrorefined naphthenic oil and from 50-25 percent of a dewaxed paraffinic oil, said blend containing in the range of 15-35 weight percent aromatics, having an SUS viscosity at F. in the range of 100-500 and a natural floc point no higher than 35 F. in CCI F refrigerant.

2. The composition of claim 1 and having a basic nitrogen content no greater than 10 ppm.

3. The composition of claim 2 wherein no greater than 2.5 Wt. CHClF is determined after l4-days of scaled tube stability testing at 347 F. with CCI F refrigerant in the presence ofa steel strip.

4. The composition of claim 1 and having better thermal stability than a naphthenic refrigeration oil of about the same viscosity at 100 F.

5. The composition of claim 4 and which, compared with said naphthenic refrigeration oil, produces significantly less coke deposit on throttle valves when used for about 2,000 hours in a compressor which is operated at an average coil temperature in the range of l40l70 F.

6. The composition of claim 5 wherein the basic nitrogen content is less than 5 ppm and wherein no greater than 1.0 Wt. percent of CHClF is determined after l4-days of sealed tube stability testing at 347 F.

with CCl F refrigerant in the presence ofa steel strip.

7. A composition according to claim 1 wherein said hydrorefined naphthenic oil has a viscosity at 100 F. in the range of l00-750 SUS and wherein at least 50 volume percent of said dewaxed paraffinic oil distills above 900 F., the distillation being corrected to one atmosphere.

8. A composition according to claim 7 and having a viscosity at 100 F. in the range of -300 SUS.

9. A composition according to claim 1 and having a viscosity at 100 F. in the range of -250 SUS. 

1. A composition, useful as a refrigerator oil, comprising a blend of from 50-75 volume percent of a hydrorefined naphthenic oil and from 50-25 percent of a dewaxed paraffinic oil, said blend containing in the range of 15-35 weight percent aromatics, having an SUS viscosity at 100* F. in the range of 100-500 and a natural floc point no higher than -35* F. in CCl2F2 refrigerant.
 2. The composition of claim 1 and having a basic nitrogen content no greater than 10 ppm.
 3. The composition of claim 2 wherein no greater than 2.5 Wt. CHClF2 is determined after 14-days of sealed tube stability testing at 347* F. with CCl2F2 refrigerant in the presence of a steel strip.
 4. The composition of claim 1 and having better thermal stability thaN a naphthenic refrigeration oil of about the same viscosity at 100* F.
 5. The composition of claim 4 and which, compared with said naphthenic refrigeration oil, produces significantly less coke deposit on throttle valves when used for about 2,000 hours in a compressor which is operated at an average coil temperature in the range of 140*-170* F.
 6. The composition of claim 5 wherein the basic nitrogen content is less than 5 ppm and wherein no greater than 1.0 Wt. percent of CHClF2 is determined after 14-days of sealed tube stability testing at 347* F. with CCl2F2 refrigerant in the presence of a steel strip.
 7. A composition according to claim 1 wherein said hydrorefined naphthenic oil has a viscosity at 100* F. in the range of 100-750 SUS and wherein at least 50 volume percent of said dewaxed paraffinic oil distills above 900* F., the distillation being corrected to one atmosphere.
 8. A composition according to claim 7 and having a viscosity at 100* F. in the range of 125-300 SUS. 